The use of bleaching catalysts for stain removal has been developed over recent years.
The search for new classes of compounds that are suitable as peroxyl catalysts is ongoing.
Various [3.3.1] bicyclo compounds and complexes thereof are discussed in the literature, see for example: Comba P. et al., J. Chem. Soc. Dalton Trans, 1998, (23) 3997-4001; Börzel et al. Chem. Eur. J. 1999, 5, No. 6, 1716 to 1721 and review by P. Comba in Coordination Chemistry Reviews 2000, 200-202, 217 to 245, entitled “Coordination compounds in the Entactic State”. These compounds are discussed in terms of their physical properties.
WO0060045, to Proctor and Gamble, discloses a bleaching system comprising: a) from about 1 ppb, by weight of a transition metal catalyst comprising: i) a transition metal; ii) a ligand having formula (I):
wherein each R is independently hydrogen, hydroxyl, C1-C4 alkyl, and mixtures thereof; R1 is C1-C4 alkyl, C6-C10 aryl, and mixtures thereof; R2 is C1-C4 alkyl, C6-C10 aryl, and mixtures thereof; R3 and R4 are each independently hydrogen, C1-C8 alkyl, C1-C8 hydroxyalkyl, —(CH2)xCO2R5 wherein R5 is C1-C4 alkyl, x is from 0 to 4, and mixtures thereof; X is carbonyl, —C(R6)2— wherein each R6 is independently hydrogen,hydroxyl, C1-C4 alkyl, and mixtures thereof; b) optionally a source of hydrogen peroxide; and c) the balance carriers and adjunct ingredients. However, the teaching of WO0060045 limits substituents at the nitrogens (3 and 7 positions) of bicyclostructure to homoaromatic carbon groups, namely alkyl and aryl.
WO0248310, to Unilever, in contrast to WO0060045 discloses compounds having a similar core structure but with the requirement that at least one of R1 and R2 is a group containing a heteroatom capable of coordinating to a transition metal.